Biocontrol efficacy of 2-pyrroldione-5-carboxylic acid (2Py-5CA), an antifungal bioactive macromolecule from the endophyte Penicillium oxalicum , against Ramularia collo-cygni in barley

Abstract Global crop production suffers significant losses (23%) due to disease caused by fungal pathogens. Biocontrol agents may be sustainable alternatives to fungicides for disease management. Ramularia leaf spot (RLS), caused by Ramularia collo-cygni (RCC), is a widespread disease of barley (Hordeum vulgare). Two Penicillium oxalicum isolates identified from a collection of endophytes from wild barley, suppress development of R. collo-cygni and exhibit functional plant growth attributes in vitro. Analysis of the P. oxalicum culture filtrate revealed antifungal activity common to both isolates. An untargeted metabolomics (LC-MS/MS) approach uncovered the secondary metabolite profile of the P. oxalicum endophytes including the identification of 2Py-5CA as an antifungal. AntiSMASH-based genome mining identified a non-ribosomal peptide synthetase (NRPSs) biosynthetic gene cluster in P. oxalicum responsible for producing paraherquamide and ultimately the antifungal 2Py-5CA. In vitro studies demonstrated that 2Py-5CA can also suppress growth of the cereal pathogens; Zymoseptoria tritici, Pyrenophora teres, Fusarium graminearum and the horticultural pathogen, Botrytis cinerea disrupting the growth of pathogenic fungal hyphae and spore structure development. Finally, 2Py-5CA reduced RLS symptoms when sprayed on barley seedlings. Therefore 2Py-5CA has potential as a biofungicide to combat fungal crop pathogens. Competing Interest Statement The authors have declared no competing interest.